(a) Field of the Invention
The present invention relates to a repeater system having an oscillation preventing function and a control method thereof. More specifically, the present invention relates to a repeater system interlocked with a base station transceiver system of a mobile communication system, and a control method thereof.
(b) Description of the Related Art
In general, a mobile communication system includes a base station transceiver system, a base station controller, a mobile switching center, and a mobile station.
The base station transceiver system is in communications with mobile stations in a predetermined frequency band, each mobile station having a predetermined service radius. Thus, a plurality of base station transceiver systems are properly arranged so that the service radii of the individual base station transceiver systems are overlapped, in order to extend the service area.
Although multiple base station transceiver systems cover the entire city area, there are still blanket areas, i.e., non-service areas, including underground areas of a large building, interior space of a high-rise building.
Mobile telephone subscribers can hardly have a smooth talking service in the blanket areas. Conventionally, repeater systems are installed in the blanket areas in an attempt to solve the problem in regard to the blanket areas with less expense relative to the base station transceiver systems.
Typically, several or several scores of repeater systems are connected in common to a single base station transceiver system, and the amount of noise introduced in the base station transceiver system on the reverse link increases in proportion to a rise in the number of the repeater systems connected to the base station transceiver system, thus reducing the capacity of the base station transceiver system.
The repeater systems may have self-oscillations depending on the installation place or according to circumstances. Among the self-oscillations, the forward oscillation causes no more than a failure of connection to the corresponding service area, but the reverse oscillation results in serious defects in a reception path of the base station transceiver system connected to the repeater systems.
It is an object of the present invention to solve the problem and to provide a repeater system having an oscillation preventing function and an automatic reverse output disabling function, and a control method thereof, in which the reverse output of the repeater system is disabled upon detection of a non-subscriber interval in the service area or a reverse oscillation so as to prevent a drop in the capacity of a base station transceiver system and protect a reception path.
In one aspect of the present invention, there is provided a repeater system comprising: a transmitter for amplifying data received from an external base station transceiver system, converting the amplified data to a service frequency, and sending the service frequency to a mobile station in a corresponding service area; a receiver for amplifying the signal received from the mobile station and outputting the amplified signal to the base station transceiver system; and a controller for detecting the power level of the receiver, and preventing the output signal of the receiver being sent to the base station transceiver system when the power level is above a first reference value during a first time or below a second reference value during a second time.
In another aspect of the present invention, there is provided a method for controlling a repeater system, comprising the steps of: discriminating between an oscillation signal of the repeater system, and a talking signal and an access signal, disabling a reverse output of the repeater system during oscillation of the repeater system, and after an elapse of a first time, detecting the state of power of the reverse output; disabling the reverse output of the repeater system when the power is in an oscillation state; and enabling the reverse output of the repeater system when the power not in the oscillation state and the reverse output is an access or talking signal.